Unanswered Questions
168 questions with no upvoted or accepted answers
22
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0
answers
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Is there a software that can do derivatives with respect to user defined vibrational modes?
I'm doing some property calculations that depend on a sum of derivatives of some quantity with respect to normal vibrational modes. I was hoping to find some physical intuition relating the type of ...
- 15.9k
9
votes
0
answers
248
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Different Results obtained while doing multiple runs from same inputs in VASP
I have been trying to optimize the parallelization parameters in VASP. By varying the parameters(such as KPAR and NCORE) I am trying to reduce the Elapsed time that is printed at the end of each line. ...
- 1,701
7
votes
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answers
157
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Correct method for structure optimization using DFT tools
Lets's say I want to start off DFT calculations for a material whose experimental cell constants are known. So I have two ways to get the correct structure to later on calculate, say, band structure ...
- 939
7
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176
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Is there a way to set the spin multiplicity in a VASP calculation?
I will greatly appreciate if someone can point to whether I can specify the spin multiplicity of a vasp calculation?
I am trying to get the potential energy mapping of a system with neutral slab and a ...
- 551
6
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answers
117
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Spin-orbit coupling(SOC) in geometry optimisation
When I tried including SOC during the optimization of InBi lattice constants, the lattice constant increased from 4.6 Å (without SOC) to more than 6 Å (with SOC), which seems like an 'incorrect' ...
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6
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106
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What are the parameters in PySCF's Selected Configuration Interaction code
Dear StackExchange Members,
I'm using the native PySCF implementation of selected configuration interaction (SCI). However, I can't seem to find any documentation detailing the algorithm or various ...
- 20.1k
6
votes
0
answers
77
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Benchmarking DFT vs Experimental Gaps - Confusion over Fundamental and Optical Gaps
Recently, I've come across discussions about the differences between fundamental (or electronic) bandgaps and optical bandgaps, with the two quantities differing mainly by the electron-hole binding ...
- 1,366
6
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91
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How can we calculate transverse and longitudinal optical phonon frequencies
Could you please help me to calculate the "transverse and longitudinal optical phonon frequencies" from phonopy+vasp output files?
These parameters will help me to calculate the high-...
- 61
6
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229
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Regarding use of GCMC to add water molecules
I am working on a goethite system, and wish to fill the unit cell with water molecules for AIMD simulation using quantum espresso. For this, some papers[1],[2] indicated the use of Grand Canonical ...
6
votes
0
answers
178
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DFT+U for RPA Ground State
For RPA calculations in VASP, a four step process can be utilized where the first step is to compute the occupied orbitals at either the GGA or hybrid GGA level.
I am curious with materials that are ...
- 11.6k
5
votes
0
answers
108
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Help required in reducing VASP memory usage
Good day, I trust you are well and I thank you for taking your time reading through my problem.
I am currently trying to calculate a single point energy calculation with the HSE06 functional for a ...
5
votes
0
answers
103
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How to plot temperature dependent Phonon dispersion using Quantum Espresso?
Would someone please suggest me how can I plot temperature dependent phonon dispersion using Quantum Espresso? The paper (10.48550/arXiv.2211.15571) plotted phonon dispersion at different temperatures ...
5
votes
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answers
67
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How to choose vacuum value for monolayer and heterostructure?
I have read several articles but I am confused how to choose vacuum in case of 2D materials. Should we add vacuum of 20A in one side of monolayer or 10, 10A on both side of monolayer?
Kindly suggest ...
5
votes
0
answers
41
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About alignment of 2D monolayer band structures
I need to do the alignment of band structures of one 2D monolayer. I have created some vacancies in the 2D monolayer using VASP and calculated the band gap values (GGA) corresponding to different ...
- 415
5
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0
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175
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Problem with using VASP with ase on a GPU
I am a newbie using VASP, currently I am trying to calculate the formation energy per atom and pre bandgap using DFT with VASP on a GPU machine.
I wrote the following script for calculating the ...
- 241